Embodiments of the present invention relate to an engagement structure, a backlight module and a display device.
Currently, a backlight module is assembled mainly by a combination of an external metal frame and a mold frame in backlight. FIG. 1 is a schematic view showing an existing engagement structure for fixing an arrangement of a back cover and a metal frame. As shown in FIG. 1, the back cover 31 engages with the metal frame 33 by a punch structure indicated by the elliptical area, which eventually leads to the bonding of the metal frame 33 and the mold frame 32. FIG. 2 is a schematic view showing an existing engagement structure for fixing an arrangement of the back cover and the mold frame. As shown in FIG. 2, the mold frame 2 protrudes from the opening at the corner of the back cover 41 so as to achieve engagement with the back cover 41, and the engagement is further reinforced by the external metal frame 43. The engagement structure for combining the back cover 41 and the mold frame 42 is shown in the elliptical area in FIG. 2. Thus, both of the two structures mentioned above need to use metal frame, which leads to rather complex design and processing procedure. Besides, during assembling the mold frame 42 and the metal frame 43, due to the friction between these two, foreign matters are likely to occur and affect the display quality of the liquid crystal panel.
In the prior art, to reduce the cost and technical complexity of using metal frame, a design of structure without metal frame is proposed. As shown in FIG. 3, the back cover 51 with a punch structure indicated by the elliptical area engages with the mold frame 52, thus achieving the assembly of the backlight module. As shown in FIG. 4, the back cover 61 with a hemming structure indicated by the elliptical area engages with the mold frame 62, thus achieving the assembly of the backlight module. Thus, neither of the two structure designs mentioned above needs to use a metal frame, so that the cost and technical complexity is reduced compared with the design with metal frame. However, the existing structure design without a metal frame, especially for the back cover 61 with a hemming structure as shown in FIG. 4, due to the complexity in itself, leads to an increased cost of a mould for the back cover. Besides, the existing design without a metal frame increases the extension dimension of the display panel, hence not suitable for some small-size liquid crystal panel. Herein, the extension dimension of the display panel is the area between the edge of a liquid crystal display screen and a corresponding edge of the display panel.